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Novel C_(sf)/SiBCN composites prepared by densifying C_(sf)/MA-SiBCN with the PIP process:Oxidation behavior and damage mechanism

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Journal of Advanced Ceramics 2024年第5期13卷 666-678页

作者： Wenhao Dou Daxin Li Bingzhu Wang zhihua yang Jun Chen Dechang Jia Ralf Riedel Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China Key Laboratory of Advanced Structural-Functional Integration Materials and Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001China Chongqing Research Institute of HIT Chongqing 401135China Beijing Institute of Control Engineering Beijing 100094China Institut für Materialwissenschaft Technische Universität DarmstadtDarmstadt D-64287Germany School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

To improve the oxidation resistance of short carbon fiber(C_(sf))-reinforced mechanically alloyed SiBCN(MA-SiBCN)(C_(sf)/MA-SiBCN)composites,dense amorphous C_(sf)/SiBCN composites containing both MA-SiBCN and polymer-derived ceramics SiBCN(PDCs-SiBCN)were prepared by repeated polymer infiltration and pyrolysis(PIP)of layered C_(sf)/MA-SiBCN composites at 1100℃,and the oxidation behavior and damage mechanism of the as-prepared C_(sf)/SiBCN at 1300–1600℃ were compared and discussed with those of C_(sf)/*** C_(sf)/MA-SiBCN composites resist oxidation attack up to 1400℃ but fail at 1500℃ due to the collapse of the porous framework,while the PIP-densified C_(sf)/SiBCN composites are resistant to static air up to 1600℃.During oxidation,oxygen diffuses through preexisting pores and the pores left by oxidation of carbon fibers and pyrolytic carbon(PyC)to the interior of the *** to the oxidative coupling effect of the MA-SiBCN and PDCs-SiBCN matrices,a relatively continuous and dense oxide layer is formed on the sample surface,and the interfacial region between the oxide layer and the matrix of the as-prepared composite contains an amorphous glassy structure mainly consisting of Si and O and an incompletely oxidized but partially crystallized matrix,which is primarily responsible for improving the oxidation resistance.

关键词： mechanically alloyed SiBCN(MA-SiBCN) polymer-derived ceramics SiBCN(PDCs-SiBCN) short carbon fiber-reinforced SiBCN(C_(sf)/SiBCN)composites polymer infiltration and pyrolysis(PIP) oxidation damage mechanism

Fabrication of dense SiBCN monolith at a lower temperature and its high-temperature performance

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Journal of Advanced Ceramics 2024年第8期13卷 1198-1211页

作者： Zi-Bo Niu Daxin Li Dechang Jia zhihua yang Kunpeng Lin Yan Wang Paolo Colombo Ralf Riedel Yu Zhou Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150080China Key Laboratory of Advanced Structural-Function Integrated Materials and Green Manufacturing Technology Ministry of Industry and Information TechnologyHarbin 150080China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150080China Department of Industrial Engineering University of PadovaPadova 3513iItaly Department of Materials Science and Engineering The Pennsylvania State UniversityUniversity Park 16802USA Institute of Materials Science Darmstadt University of TechnologyDarmstadt 64287Germany School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

In this study,a crack-free pyrolysis process of partially cured precursor powder compacts was developed to prepare dense silicon boron carbonitride(SiBCN)monoliths at much lower temperatures(1300℃),thereby circumventing the challenges of sintering densification(>1800℃).Unlike the elastic fracture in over-cured precursors or the viscoelastic deformation in under-cured precursors,the partially cured precursor,exhibiting elastic-plastic deformation behavior,facilitates limited nanoscale pore formation in a dense structure,achieving a balance between crack-free pyrolysis and *** to SiBCN derived from the over-cured precursor(σ=~159 MPa,K_(IC)=1.9 MPa:m^(1/2),Vickers hardness(HV)=7.8 GPa,and E=122 GPa),the resulting SiBCN monolith exhibited significantly improved mechanical properties(σ=~304 MPa,K_(IC)=3.7 MPa-m12,HV=10.6 GPa,and E=161 GPa)and oxidation *** addition,this study investigated the high-temperature performance of SiBCN monoliths,including crystallization and oxidation,and determined the oxidation kinetics induced by pore structure healing and the different oxidation mechanisms of Si-C-N and B-C-N clusters in the amorphous *** to its unique composition and structure,the SiBCN ceramic oxide layer exhibits exceptional self-healing effects on repairing the nanoporous system in the initial stage and shows outstanding high-temperature stability during prolonged oxidation,mitigating adverse effects from bubble formation and *** to the nanoporous structure,the oxidation rate is initially controlled by gas diffusion following a linear law before transitioning to oxide layer diffusion characterized by a parabolic ***,due to different valence bond configurations,Si-C-N transforms into an amorphous SiCNO structure after phase separation,unlike the nucleation and growth of residual B-N-C.

关键词： silicon boron carbonitride(SiBCN)ceramics crack-free pyrolysis amorphous structure oxidation mechanisms kinetic law

Characterization and spatial analysis of coseismic landslides triggered by the Luding Ms 6.8 earthquake in the Xianshuihe fault zone, Southwest China

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Journal of Mountain Science 2024年第1期21卷 160-181页

作者： GUO Changbao LI Caihong yang zhihua NI Jiawei ZHONG Ning WANG Meng YAN Yiqiu SONG Deguang ZHANG Yanan ZHANG Xianbing WU Ruian CAO Shichao SHAO Weiwei Institute of Geomechanics Chinese Academy of Geological SciencesBeijing 100081China Key Laboratory of Active Tectonics and Geological Safety Ministry of Natural ResourcesBeijing 100081China Research Center of Neotectonism and Crustal Stability China Geological SurveyBeijing 100081China School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Sichuan Institute of Geological Survey Chengdu 610081China

On September 5, 2022, a magnitude Ms 6.8 earthquake occurred along the Moxi fault in the southern part of the Xianshuihe fault zone located in the southeastern margin of the Tibetan Plateau,resulting in severe damage and substantial economic loss. In this study, we established a coseismic landslide database triggered by Luding Ms 6.8 earthquake, which includes 4794 landslides with a total area of 46.79 km^(2). The coseismic landslides primarily consisted of medium and small-sized landslides, characterized by shallow surface sliding. Some exhibited characteristics of high-position initiation resulted in the obstruction or partial obstruction of rivers, leading to the formation of dammed lakes. Our research found that the coseismic landslides were predominantly observed on slopes ranging from 30° to 50°, occurring at between 1000 m and 2500 m, with slope aspects varying from 90° to 180°. Landslides were also highly developed in granitic bodies that had experienced structural fracturing and strong-tomoderate weathering. Coseismic landslides concentrated within a 6 km range on both sides of the Xianshuihe and Daduhe fault zones. The area and number of coseismic landslides exhibited a negative correlation with the distance to fault lines, road networks, and river systems, as they were influenced by fault activity, road excavation, and river erosion. The coseismic landslides were mainly distributed in the southeastern region of the epicenter, exhibiting relatively concentrated patterns within the IX-degree zones such as Moxi Town, Wandong River basin, Detuo Town to Wanggangping Township. Our research findings provide important data on the coseismic landslides triggered by the Luding Ms 6.8 earthquake and reveal the spatial distribution patterns of these landslides. These findings can serve as important references for risk mitigation, reconstruction planning, and regional earthquake disaster research in the earthquake-affected area.

关键词： Luding earthquake Coseismic landslides Remote sensing interpretation Spatial distribution Xianshuihe fault Earthquake fault

新书介绍——《中国区域岩片抽拉大地构造图(1∶500万)》

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地质论评 2024年第3期70卷 1120-1120,1126页

作者：杨高学长安大学地球科学与资源学院西安710054

由长安大学地球科学与资源学院杨志华教授主编的《中国区域岩片抽拉大地构造图(1∶500万)简要说明》已于近日在地质出版社正式出版发行!该图及简要说明是按杨志华教授创立的抽拉构造理论体系编制而成,这可能在国内外尚属首次。迄今为止... 详细信息

由长安大学地球科学与资源学院杨志华教授主编的《中国区域岩片抽拉大地构造图(1∶500万)简要说明》已于近日在地质出版社正式出版发行!该图及简要说明是按杨志华教授创立的抽拉构造理论体系编制而成,这可能在国内外尚属首次。迄今为止尚未见到创立的地槽—地台学说和板块构造学说编制相应的大地构造图。

关键词：大地构造图板块构造学说地质出版社地球科学岩片抽拉构造新书介绍地台

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基于改进哈里斯鹰算法的系统能效优化

华中科技大学学报（自然科学版） 2024年第3期52卷 58-64页

作者：苏佳杨志华刘彦明河北科技大学信息科学与工程学院河北石家庄050018 上海交通大学电子信息与电气工程学院上海200030

为有效提升多小区多用户通信系统能效,针对哈里斯鹰优化算法易陷入局部最优导致无法得到最优系统能效这一问题,提出一种改进的哈里斯鹰能效优化算法.首先,建立考虑小区间干扰因素的多小区多用户通信系统模型,得出该系统的能量效率方程;... 详细信息

为有效提升多小区多用户通信系统能效,针对哈里斯鹰优化算法易陷入局部最优导致无法得到最优系统能效这一问题,提出一种改进的哈里斯鹰能效优化算法.首先,建立考虑小区间干扰因素的多小区多用户通信系统模型,得出该系统的能量效率方程;在运用哈里斯鹰算法求解系统能效过程中,将Sobol混沌初始化与莱维飞行变异策略结合到算法中以对原始算法进行改进.仿真结果表明:相较于原始算法,本文算法改善了原算法陷入局部最优问题,并将系统能效提高了15.1%.

关键词：多小区多用户通信系统小区间干扰能量效率哈里斯鹰优化算法局部最优

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虚拟实践何以成为检验真理的标准

福建师范大学学报（哲学社会科学版） 2024年第4期 23-32,171页

作者：盛晓薇杨志华中共宁夏区委党校(宁夏行政学院)马克思主义学院宁夏银川750021 北京林业大学马克思主义学院北京100083

数字智能时代新出现的虚拟实践,给马克思主义实践观、认识论提出了新的时代课题。根据马克思主义的观点,实践是检验认识真理性的唯一标准,任何认识都应当通过产生这种认识和由这种认识指导的客观性实践或逻辑证明来证实或证伪。然而,学... 详细信息

数字智能时代新出现的虚拟实践,给马克思主义实践观、认识论提出了新的时代课题。根据马克思主义的观点,实践是检验认识真理性的唯一标准,任何认识都应当通过产生这种认识和由这种认识指导的客观性实践或逻辑证明来证实或证伪。然而,学界有观点认为虚拟实践可以提高人们的认知能力和认识水平,却不能检验认识是否具有真理性,这对马克思主义实践观和以实践为基础的认识论的科学性都带来了一定挑战。事实上,虚拟实践在本质上是人的现实实践在虚拟世界的延伸,它作为一种实践活动也可以检验认识的真理性,具体而言主要通过三种方式检验:通过模拟现实世界中实际发生的事件或行为对认识进行检验,通过虚拟实验对科学上的各种假说进行检验,通过在虚拟情景中运用逻辑证明方法来检验。虚拟实践的出现确实丰富了检验认识真理性的方式、内容以及主体的思维方式,但并没有否证马克思主义科学的认识论命题,马克思主义关于“实践是检验真理的唯一标准”的论断并没有过时。

关键词：虚拟实践马克思主义实践观实践标准真理真理性认识论

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数据驱动的新型非线性光学材料理论设计研究进展

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人工晶体学报 2024年第9期53卷 1475-1493页

作者：储冬冬杨志华潘世烈中国科学院新疆理化技术研究所晶体材料研究中心

非线性光学晶体是全固态激光器的核心器件，在信息技术、国防安全等方面具有广泛且重要的应用。随着高性能计算技术的发展，计算辅助实验的“自上而下”靶向设计逐渐成为非线性光学材料设计的重要组成部分。同时，基于高通量计算获取的... 详细信息

非线性光学晶体是全固态激光器的核心器件，在信息技术、国防安全等方面具有广泛且重要的应用。随着高性能计算技术的发展，计算辅助实验的“自上而下”靶向设计逐渐成为非线性光学材料设计的重要组成部分。同时，基于高通量计算获取的大规模结构性能信息，进一步为数据挖掘、机器学习的算法训练提供了坚实的数据基础，促进了材料设计的第四范式的发展。本文从非线性光学晶体的计算材料设计入手，探讨了数据驱动的非线性光学理论设计的新范式，对本团队近年来在高通量筛选、晶体结构预测以及机器学习加速非线性光学材料设计等方向的研究进展进行了综述。

关键词：晶体结构预测高通量筛选机器学习非线性光学材料材料设计

来源：博看期刊

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双离合自动变速器首次启动排气策略研究

上海汽车 2024年第7期 49-53页

作者：杨志华上汽集团创新研究开发总院上海201804

某湿式双离合自动变速器存在发动机停机后,首次启动1挡升2挡时,偶数离合器压力跟随较差的问题,导致整车起步缓慢、换挡顿挫。文章结合仿真分析找出问题产生的原因,并通过台架测试对排气效果进行验证,最终实车验证了排气策略的有效性,解... 详细信息

某湿式双离合自动变速器存在发动机停机后,首次启动1挡升2挡时,偶数离合器压力跟随较差的问题,导致整车起步缓慢、换挡顿挫。文章结合仿真分析找出问题产生的原因,并通过台架测试对排气效果进行验证,最终实车验证了排气策略的有效性,解决了发动机停机后首次1挡升2挡的换挡问题。

关键词：双离合器变速器排气

以LiB_(3)O_(5)为模板设计深紫外零级波片材料

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Science China Materials 2024年第3期67卷 914-920页

作者：张志远徐蝶 Abudukadi Tudi 杨志华韩树娟潘世烈 Research Center for Crystal Materials State Key Laboratory of Functional Materials and Devices for Special Environmental ConditionsXinjiang Key Laboratory of Functional Crystal MaterialsXinjiang Technical Institute of Physics and ChemistryChinese Academy of SciencesUrumqi 830011China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

以著名的LiB_(3)O_(5)为模板,通过增强其结构中B_(2)O_(5)的夹角使双折射更小,在封闭体系中通过高温溶液法获得了两种新的用于制造零级波片的双折射晶体Li_(2)MLaB_(18)O_(30)(M=Rb,Cs).有趣的是,相邻的B_(2)O_(5)接近垂直排列,使得它... 详细信息

以著名的LiB_(3)O_(5)为模板,通过增强其结构中B_(2)O_(5)的夹角使双折射更小,在封闭体系中通过高温溶液法获得了两种新的用于制造零级波片的双折射晶体Li_(2)MLaB_(18)O_(30)(M=Rb,Cs).有趣的是,相邻的B_(2)O_(5)接近垂直排列,使得它们表现出比商用石英晶体(Δn~0.0092在可见光区域)小得多的双折射率(分别为0.0032@532 nm和0.0027@532 nm).此外,Li_(2)MLaB_(18)O_(30)(M=Rb,Cs)晶体的紫外截止边均低于200 nm,表明它们可用作深紫外区域的零级波片材料.

关键词： tiny birefringence zero-order waveplate deep-ultraviolet region angle of B_(2)O_(5)